When exposed to water and oxygen, the organic materials in OLEDs corrode quickly. Even water vapor can ruin an OLED display over time. Manufacturers have come up with complex sealing processes, but have only been moderately successful in holding back the damage. Now, researchers have developed a new nanomaterial that may allow for optimal protection for OLEDs, clearing one of the last major roadblocks to their adoption.

Researchers at the Singapore A*STAR’s Institute of Materials Research and Engineering (IMRE) developed a thin nanofilm which promises to protect not only OLEDs, but also components such as solar cells, with a moisture protection level of over 1,000 times anything currently on the market.

The UK Centre for Process Innovation analyzed the barrier and verified that it had the highest reported water vapor barrier performance to date. The new barrier promises to revolutionize the plastic electronics industry. Within five years the plastic electronics industry is expected to grow to a $23B USD market worldwide.

Current films typically have a water vapor transmission rate of around 10-3g/m2 at 25°C and 90% relative humidity (RH). Ideally barriers to organic electronic devices need to be much lower, around a millionth of a gram per square meter per day (10-6g/m2), at a slightly higher temperature of 39°C. The problems with current materials arise when pinholes, cracks and grain boundaries occur in the thin oxide barrier films deposited on the plastic, leading to ‘pore effects’ which allow water and oxygen molecules to penetrated the barrier plastic.

The current best solution to the pore problem is to alternate layers of organic and inorganic deposited on the plastic. This causes the pores to be misaligned, creating a "torturous path" for the damaging water and oxygen molecules. While this approach is reasonably effective, it increases production cost and complexity. The IMRE researchers instead looked to a novel approach to solving the problem, plugging the holes with nanoparticles. This reduces the complex multilayer barrier down to a simple, more efficient two layer barrier, with a barrier oxide layer and a nanoparticlulate sealant layer.

The handy nanoparticles used in the seal not only block the path of moisture and oxygen, but they also trap it and react with it, further decreasing transmission. The barrier let less than 10-6g/m2 of moisture in under testing. Further the lag time, or the time it took for water to penetrate the barrier, was an astounding 2300 hours (approximately 96 days) at 60°C and 90% RH. Senthil Ramadas, principal investigator of the IMRE project states, "With a level of protection that surpasses the ideal requirements for
such films to date, manufacturers now have the opportunity to extend
the lifetime of plastic electronic devices by leaps and bounds!"

One problem the team faced is exactly how to measure permeation of an extremely low permeation barrier. The team devised an improved water and oxygen pentetration measurement device, that can detect levels of less than 10-8g/m2. The new test has already been put to use in various service industry projects. Says Senthil, "Together with our expertise in encapsulation processes and permeation
measurement technologies we are also able to provide a total solution
package for industries such as flexible solar cells and OLED displays
producers."

The research has been funded by Exploit Technologies Pte Ltd (ETPL), the commercialization branch of A*Star, due to its promise. Boon Swan Foo, the Executive Chairman of ETPL states, “Exploit
Technologies sees commercial potential in A*STAR IMRE’s breakthrough
barrier film technology. It has excellent promise for enabling the fast
growing plastic electronics industry. We want to take this technology
from the lab to the market.”

The IMRE research team is already in talks with solar cell, lighting industry, and flexible display manufacturers, it says. The center has already signed agreements with a number of companies to commercialize the technology, including a collaboration agreement with G24Innovations, a major thin film solar cell company, as well as an agreement with Asian electronics manufacture KISCO.

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This article is over a month old, voting and posting comments is disabled

quote: If one layer can be this effective at resisting water vapor, will two layers provide better performance? I'm confused by the fact that the water vapor transmission rate specified is in g/m2, which emphasizes surface area, which means that this material's performance is independent of thickness...

The Oled were also designed with two thoughts, to be ultra thin, and some were able to be rolled. Adding another layer would hinder the purpose of the design intent.

I don't know who's idea it is, but I'm more than content with a monitor being 2" thick, they're aiming for less than 1" thickness. Hehe, some people are also thinking sci-fi, no thickness at all, just light emitted into thin air.